The present invention relates to novel lubricating composition effective in the reduction of friction or rubbing in turning machines operating in a mixed lubrication system, comprising an overbased lubricating oil and a small percentage of an additive compatible with this oil.
Overbased oils have already been used as a lubricant for turning machines, and, in particular, for internal combustion engines, whether operated with gasoline or of the diesel type. These overbased oils are characterized by a high T.B.N. (total basic number), for example, between 10 and 20. Their basic character allows to neutralization of the organic and mineral acids formed during thermal decomposition occuring in the lubricant. Generally, the basic character of these lubricants results from the presence of overbased calcium salts, for example, overbased calcium sulfonate or phenate.